1. Field of the Invention
The present invention relates to a circuit board and a method for manufacturing the same, and more particularly, to a circuit board with a via structure which has a vertically perpendicular side surface and can implement a fine pitch, and a method for manufacturing the same.
2. Description of the Related Art
As the miniaturization and thinning of electronic components progress, there is also an increasing demand for miniaturization and thinning of package substrates and printed circuit boards, and there is also a demand for high fine pitch of metal vias such as a normal via, a blind via, and a buried via which are applied to these electronic substrates.
The levels of fine pitch required for a via structure applied to the recent package substrates and printed circuit boards are that the width of a via pad is less than 15 μm, the width of a via is less than 5 μm, and the interval between the vias is less than 30 μm. However, since the conventional vias are usually formed to have an inclined side surface, there are limitations in reducing the interval between the vias. Further, when the thickness of a resist layer used as an interlayer insulating layer is large, the conventional via forming techniques have difficulty in implementing an integrated via structure due to difficulty in forming a precise via hole. Particularly, when the thickness of the resist layer is greater than 2 μm, further greater than 10 μm, since it reaches the limits of resolution of a photolithography process, there is a demand for techniques that can form an integrated via structure regardless of the thickness of a resist layer.